A biochemcial quantitative method to follow ligands and receptors through clathrin-coated regions of the cell has been developed. These studies implicate coated pits in the Golgi region as having a crucial role in sorting and directing ligands and recptors to lysosomes. PMA induces the entry of the EGF receptor via coated pits but does not direct it to lysosomes. Instead, the receptor reappears on the surface after 30 minutes.